1. Field of the Invention
The present invention relates to a front fork in a two-wheeled motor vehicle or the like.
2. Description of the Related Art
In a conventional, front fork in a two-wheeled motor vehicle, as described in Japanese Unexamined Utility Model Publication No. 60-157496, there is a structure in which an inner tube in a vehicle body side is slidably inserted into an outer tube in a wheel side. A hollow pipe is erected in a bottom portion of the outer tube. A piston portion provided in an upper portion of the hollow pipe is slidably provided on an inner periphery of the inner tube. An oil chamber provided in an outer side of the hollow pipe is sectioned into upper and lower sides by a piston provided in a leading end portion of the inner tube. An oil reservoir chamber communicating with the oil chamber is provided in an inner side of the hollow pipe, and a gas chamber in an upper portion of the oil reservoir chamber is provided in the interior of the inner tube.
In the prior art, a partition wall member sectioning the oil reservoir chamber into upper and lower sides is provided in the upper portion of the hollow pipe. The partition wall member is provided in parallel with a compression side flow passage and an expansion flow passage which communicates the upper and lower oil reservoir chambers. The compression side flow passage is provided with a compression side slide valve and a spring for opening the slide valve when working fluid reaches a fixed flow speed at a middle piston speed range, thereby generating a compression side damping force. The expansion side flow passage is provided with an expansion side check valve.
The prior art has the following problems.                (1) Since the compression side flow passage and the expansion side flow passage are provided in parallel in the partition wall member, a stroke is changed from an expansion stroke to a compression stroke while the expansion side check valve is not completely closed, particularly when being changed from the expansion stroke to the compression stroke. There is generated a phenomenon that the working fluid flows from the expansion side flow passage without passing through the compression side flow passage during compression, so that a response of the damping force when changing between the expansion and compression strokes is deteriorated.        (2) The compression side damping force is generated by the slide valve, in place of a deflection valve. Accordingly, it is impossible to obtain a damping force based on a deflection property of the deflection valve in the middle piston speed range. No buckling feeling (no damping feeling) is generated in the middle speed range.        (3) The compression side damping force is set and changed only by a spring constant of a spring energizing the slide valve and adjustment of a set load. There is no freedom of setting and changing the damping force.        